1. Field of the Invention
The present invention relates to styrenic polymers of improved impact strength, and in particular to polymers of p-methylstyrene wherein both a thermoplastic elastomer and a non-thermoplastic diene elastomer are incorporated during the polymerization.
2. Description of the Prior Art
Polymers derived from styrene have been commercially applied for many years, including the "high impact" modifications in which the impact strength is improved by incorporating a minor amount of a rubber during the polymerization. More recently, polymers derived from poly(p-methylstyrene) have been described, as has the production of "high impact" modifications of such polymers by the grafting of methylstyrene onto an elastomeric polymer backbone. See, e.g., U.S. Pat. Nos. 4,260,694 and 4,275,179 and European patent application No. 3405. However, there remains a continuing need to improve the impact resistance of p-methylstyrene polymers.